HERMANN VON HELMHOLTZ 



processes in nature ; while, in regard to irreversible 

 processes as, for example, in the generation and con- 

 duction of heat the irreversibility appeared to depend, 

 not upon the essential nature of things, but upon the 

 limitation of our powers in reducing to order again 

 haphazard motions of molcules, or in reversing the 

 molecular movements associated with the transference 

 of heat. 



The outcome of this discussion is to show that in 

 the mechanical operations of nature, there is simplicity 

 and economy. The members of a system, free to 

 move amongst each other, and unaffected by any 

 external system, may have many paths along which 

 they might pass from one position to another, so as 

 to make a change from one configuration to another, 

 but they always travel by the best possible route, and 

 thus bring about the change in a simple way. What 

 the real significance of this is we do not know, and 

 we must eliminate from the conception the notion of 

 choice. It may yet be shown why this must be so. 

 This principle, apparently, has universal application, 

 and it is the guide in many investigations. 



In his paper on Maxwell's theory of movements in 

 the free ether, already referred to (p. 219), Helmholtz 

 plunges into questions of an extremely difficult nature, 

 and on which all his powers of mathematical analysis 

 and his capacity of wielding, like an intellectual Titan, 

 the tremendous principles of the conservation of energy 

 and of least action, are brought to bear. Ponderable 

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